Suppressing resonance in transformer winding under very fast transient overvoltage

Abstract

This paper presents a new method for suppressing internal resonance in power transformers connected to gas insulated substation (GIS) due to very fast transient overvoltage (VFTO) in the GIS. Internal resonance within the transformer windings will take place if one of VFTO frequencies matches with the power transformer natural frequency. In this context, the parameters affecting internal transformer resonance are investigated through the simulation of 400kV GIS connected to a 250MVA, three phase transformer and a new suppressing method for internal transformer resonances is proposed. In contrary with existing resonance suppressing approaches that call for modifications in the GIS structure, the proposed method in this paper can be employed with any existing GIS without any change in its structure.